Turbine shrouding



April 6, 1943. c. c. FRANCK TURBINE SHROUDING' Filed Feb. 14, 1942 a4 23161: aa'

INVENTOR CLRRENCE C. FRR'NCK.

7b, 0 km ATTORNEY Patented Apr. 6, 1943 TURBINE SHROUDING Clarence C.Franck, Swarthmore, Pa., assignor to Westinghouse Electric &Manufacturing Company, East Pittsburgh, Pa., a corporation ofPennsylvania Application February 14, 1942, Serial No. 430,843

4 Claims.

The invention relates to turbine blading of the shrouded type and it hasfor an object to provide a shroud construction comprised by overlappingshroud portions formed integral with the blades and riveted together.

A further object of the invention is to provide a shroud constructionfor a row of blades which is comprised by lapping elements formedintegrally with the blade and connected by rivets positioned so as to besubject to minimum bending stresses.

A further object of the invention is to provide a shroud constructionfor a row of blades which is comprised by shroud elements or portionsintegral with the blades, each shroud element including spaced tonguesor portions extending from the concave face of its blade and disposedadjacent to the side edges thereof and a tongue or portion extendingfrom the convex face of the blade and having a width conforming to andpositioned so as to fit between tongues extending from the concave faceof the adjacent blade together with rivets for connecting theinterfitting tongues, the tongues being so arranged as to avoidoverlapping of blade sections thereby.

These and other objects are effected by the invention as will beapparent from the following description and claims taken in connectionwith the accompanying drawing, forming a part of this application, inwhich:

Fig. l is a sectional detail view showing one embodiment of theinvention;

Fig. 2 is a plan view of the shroud construction of Fig. 1;

Fig. 3 is a sectional view taken along the line I III- -III of Fig. 2;

Fig. 4 is a view similar to Fig. 1, but showing a modified form ofshroud construction;

Fig. 5 is a plan view of the shroud construction of Fig. 4;

Fig. 6 is a sectional view taken along the line VI-VI of Fig. 5;

Fig. 7 is a view similar to Fig. l, but showin a further modified formof the shroud construction;

Fig. 8 is a plan view of the shroud construction of Fig. '7; and,

Fig. 9 is a sectional View taken along the line IXIX of Fig. 8.

In Fig. 1, there are shown a plurality of blades ID of a row, the bladeshaving root portions 1| arranged circumferentially in contiguousrelation. A shroud construction, at 12, is provided for the tips orouter ends of the blades Hi, the shroud construction including lappingportions I4 and I5 formed integrally with the blades, extendingcircumferentially so as to overlap in tangential planes, and connectedby rivets l6 which extend radially with respect to the blade row.

As the rivets l6 extend substantially centrally of the mid-section ofthe blade passage, they are positioned where th bending moment is aminimum, that is, the rivets are subjected to mini mum bending stresses.

Figs. 4, 5, and 6 illustrate an embodiment wherein the shroudconstruction at 12a for the blade row is comprised by lapping portionsor tongues l8 and a lapping portion or tongue l9 formed as parts of theshroud element 20 integral with each blade Illa. The lapping portions 18extend forwardly of the concave face of each blade and the portion l9extends rearwardly of the convex face thereof so that they do notoverlap the blade section. The lapping portions l8 extend to the sidesof the blade and are spaced so as to receive the portion IQ of theadjacent blade.

The lapping portions l8 and I9 overlap in radial planes and areconnected by rivets l6a extending substantially parallel to the axis ofrotation.

Aside from the arrangement shown in Figs. 4, 5, and 6 not having any ofthe lapping portions overlapping the blade sections, whereby cutting ofthe latter to provide for interfitting of the shroud construction isavoided, this arrangement provides for a relatively strong rivetedconnection in that each of the rivets ltd acts in double shear.

The embodiment shown in Figs. 7, 8 and 9 is similar to that justdescribed with respect to having the lapping portions overlap in radialplanes. It diliers therefrom in that each blade is provided with tonguesor overlapping portions 22 and 23 extending in opposite directions, thelapping portions 22 and 23 of adjacent blades overlapping in radialplanes and being connected by the rivets lEb extending parallel to theturbine axis. Assuming that the lapping portions or tongues 23 extendrearwardly of the convex faces of the blades, it will be apparent thatit is necessary to cut back the shroud element 24 of each blade so thatthe tongue 23 of the adjacent blade may overlap a portion of the bladsection of the first blade, as shown in Fig. 8.

While the invention has been shown in several forms, it will be obviousto those skilled in the art that it is not so limited, but issusceptible of various other changes and modifications without departingfrom the spirit thereof, and it is desired, therefore, that only suchlimitations shall be placed thereupon as are specifically set forth inthe appended claims.

What is claimed is:

1. In a turbine, a rotor, a row of blades connected to the rotor anddefining blade passages, and a shroud construction for the blades; saidshroud construction including lapping portions formed integrally withthe blades and extending from the concave and convex faces of the latterso as to overlap and cover the blade passages and rivets for connectingthe overlapping portions, th rivet for the overlapping portions of eachblade passage being so located that the stress area effective to connectthe overlapping portions is located substantially midway of the width ofthe blade passage.

2. The combination as claimed in claim 1, wherein the lapping portionsoverlap in tangential planes and are connected by rivets which extendradially with respect to the rotor.

3. The combination as claimed in claim 1, wherein the lapping portionsoverlap in radial planes and ar connected by rivets extendingsubstantially parallel to the turbine axis.

4. In a turbine, a rotor, a row of blades connected to the rotor anddefining blade passages, and a shroud construction for the blades; saidshroud construction including lapping portions formed integrally withthe blades, said lapping portions including a pair of spaced lappingportions extending from the concave face of each blade and adjoining theside edges of th latter and a portion extending from the convex face ofthe blade and arranged to fill the space between the pair of lappingportions extending from the concave face of the adjacent blade andoverlap the latter lapping portions, said lapping portions being soformed as to avoid overlapping of sections of the blades and to coverthe blade passages, and rivets for connecting the overlapped lappingportions and extending substantially parallel to the turbine axis, therivet for the overlapping portions of each blade passage being solocated that the stress area effective to connect the overlappingportions is located substantially midway of the Width of the bladepassage.

CLARENCE C. FRANCK.

